The present invention relates to a fluid torque converter, and more particularly relates to an improvement in the construction of a fluid torque converter of the general type disclosed in Japanese Patent Applications Nos. 50-157478 and 53-61266, to which U.S. Pats. Nos. 4,044,556 and 4,186,557 correspond, respectively.
An automatic transmission for an automotive vehicle conventionally includes a fluid torque converter, which provides a fluid coupling between the internal combustion engine of the vehicle and the gear transmission mechanism thereof, thus eliminating the need for any clutch system for the drive train of the vehicle, and allowing for the vehicle to be stationary while the internal combustion engine is turning at a low rotational speed at or close to the idling speed without the engine stalling, as well as providing torque multiplication by fluid flow in a per se well known way when the vehicle is being accelerated at relatively low speed and relatively low engine rotational speed. Many such torque converters are of course presently well known. Generally, such a torque converter comprises: a housing or outer shell of a generally toroidal shape, on the inside of which there are formed a series of vanes which constitute a pump impeller, and on the inside of which vanes there is fixed a pump impeller inner shell, said pump impeller being rotationally fixed to a power input shaft; a turbine member mounted within the housing as rotationally fixed to a power output shaft, formed with an outer shell on the inside of which there are formed a series of vanes, on the inside of which vanes there is fixed a turbine member inner shell; and a stator member formed with an outer shell on the inside of which there are formed a series of vanes, on the inside of which vanes there is fixed a stator member inner shell, said stator member being mounted within the housing via a one way brake on a fixed member. Thus, in such a torque converter, each of the pump impeller, the turbine member, and the stator member is formed with an inlet and an outlet, defined by the edges of its vanes which extend between its outer shell and its inner shell. The housing of such a torque converter is kept filled with hydraulic fluid, which is pumped thereinto and is also drained therefrom, and in a per se well known way the pump impeller, the stator member, and the turbine member cooperate, when the housing of the torque converter is thus filled with hydraulic fluid, to define a toroidal hydraulic fluid flow circulation system, circulation of hydraulic fluid around which in the general circulation fashion of a smoke ring is arranged to transfer torque in a conventional manner between the pump impeller and the turbine member of the torque converter. In such a hydraulic fluid flow circulation system, the hydraulic fluid passes out from the outlet of the pump impeller into the inlet of the turbine member which is closely justaposed thereto, passes through the turbine member and out of its outlet into the inlet of the stator member which is closely juxtaposed thereto, and passes through the stator member to pass out of its outlet into the inlet of the pump impeller which is closely juxtaposed thereto, to be again recirculated.
Conventionally, the cross sectional shape of a section of the outer toroidal surfaces of such a torque converter, as taken in a plane including the central axis thereof, has been approximately circular. However, in view of the great desirability of minimizing the axial length of a torque converter of an automatic transmission, in order to minimize the total axial length of the transmission - which is an important design goal in the design of automatic transmissions for front engined front wheel drive automobiles or so called FF automobiles which are becoming more and more popular nowadays - it has been proposed, in the aforementioned Patents which were filed by the same assignee as the present application, to flatten such a torque converter in its axial direction, so that such a circular cross sectional shape becomes substantially an elliptical shape, whose major axis extends in the radial direction of the torque converter, perpendicular to the central axis thereof. A fuller description of the limitations on the dimensions and construction of such a torque converter, specified in the abovementioned Patents, will be given later in the section of this specification entitled